Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 83,284	$ 33,123
Marketable securities	53,208	91,662
Restricted cash	735	734
Trade receivables, (including related parties of $6,279 and $4,251) net of allowance for doubtful accounts of $3,042 and $2,890	58,865	71,406
Assets held for sale	2,141	950
Prepaid expenses and other current assets (including related parties of $274 and $274)	13,881	11,557
Total current assets	212,114	209,432
Property and equipment, net of accumulated depreciation of $191,266 and $188,579	73,215	79,642
Intangible assets subject to amortization, net of accumulated amortization of $102,157 and $99,819 (including related parties of $6,177 and $7,098)	9,307	16,772
Intangible assets not subject to amortization	216,853	252,544
Goodwill	45,711	46,511
Operating leases right of use asset	34,394	43,837
Other assets	7,784	7,462
Total assets	599,378	656,200
Current liabilities
Current maturities of long-term debt	3,000	3,000
Accounts payable and accrued expenses (including related parties of $2,371 and $2,147)	40,711	53,931
Operating lease liabilities	7,563	9,056
Total current liabilities	51,274	65,987
Long-term debt, less current maturities, net of unamortized debt issuance costs of $1,905 and $2,226	211,095	213,024
Long-term operating lease liabilities	32,378	41,387
Other long-term liabilities	3,862	3,371
Deferred income taxes	43,229	44,259
Total liabilities	341,838	368,028
Commitments and contingencies (note 6)
Stockholders' equity
Additional paid-in capital	829,610	836,170
Accumulated deficit	(572,114)	(547,876)
Accumulated other comprehensive income (loss)	35	(131)
Total stockholders' equity	257,540	288,172
Total liabilities and stockholders' equity	599,378	656,200
Class A common stock
Stockholders' equity
Common stock	6	6
Class B common stock
Stockholders' equity
Common stock	2	2
Class U common stock
Stockholders' equity
Common stock	$ 1	$ 1